Drying apparatus and method



Feb. 26, 1929. 1,703,291

L.. BUCK DVRYING APPARATUS AND METHOD Feb. 26, 1929. 1,703,291

1 BUCK DRYING APPARATUS AND METHOD .Filed Aug. l, 1927 2 Sheet's-Sheet 2 Patentedy Feb. 26, 1929.

UNITEDl STATES PATENT OFFICE.

LUCIEN: BUC-X, OF NORTH ADAMS, MASSACHUSETTS, ASSIGNOR 0F ONE-HALF T0 JAMES HUNTER MACHINE COMPANY, 0F NORTH ADAMS, MASSACHUSETTS,A CORPORA- TION 0F MASSACHUSETTS.

DBYING APPARATUS AND METHOD.

Application led August 1,l 1927. Serial No. 209,720. v

circulation so that the rapidity of air move-` ment and air exhaustion may be adjusted to attain the maximum economy in operation. To this end, I provide means permitting 'the spiral movement vof the air into and out of the drying chamber and means ermitting the by-passing of a portion of t e-air out of the spiralgpath so that the effective pitch of the suppositious spiral is reduced. Heating elements and-draft inducing factors are located along the drying chamber, the heating chambers being separated by partitions from sections of the drying chamber and being connected thereto by inclined exhaust ducts to define the spiral movement of the air. This arrangement permits` the gradual increase in the4 temperature of the drying medium as its humidity increases so that it acquires its maximum temperature and humidity upon reaching the part of the dryer at which the articles to be dried enter.

An exhaust air duct is located adjoining the last 1of the exhaust air passages and is adapted to conduct the moisture-laden air along they chamber and to permit a portion of the exhausted air again to be returned to one ofthe draft inducing factors.

The above and further objects and advantageous features of the invention will be apparent to those skilled in the art upon a reading of the subjoined description and claims in conjunction with the accompanying drawings, in which:

Fig. v1 is a top view of the drying apparatus, the major portion thereof being removed;

Fig. 2 is a schematic view of a portion of the dryer, various partitionsbeing broken away to show the relative position of various parts;

Fig. 3 is an enlarged transverse section as indicatedI by line 3-3 of Fig. 2; and

Fig. 4 is a view corresponding to Fig.v 3

4and showing an optional form of the invention.

The improved drying apparatus comprises an elongate chamber 1 which may be made up of a plurality of substantially similar drying sections. The ends of the chamber are provided with ramps 3 and doors 2 in order to permit ready movement of conveyor racks 6 carrying articles to be dried, into and out of the dryer, and in order to close the ends of the dryer when the racks are not being moved into and out of the same. Suitable conveyor means such as the belt- 4 is located withinthe dryer and is adapted slowly to move the racks 6 or other articles therethrough. This belt may bc driven through variable speed mechanism, designated in general by the numeral 20, so that the speed of the articles bein dried may be varied in order to affor greater flexibility in the drying operations possible with drying apparatus of this character.

A motor 21 located adjoining one end of the mechanism is adapted to drive an elongate shaft 22 extending along beside the sections of the tunnel. Preferably a foraminous ceiling portion 30 is designed to emit uniformly distributed air in a direction substantially transverse to the direction of article movement through the dryer.

The downwardly flowing air passes through' the conveyor and openings 32 at the side of the tunnel into the inclined exhaust passages 33 which are defined by the inclined walls 34 between these passages and the heating chambers. A damper 35 maybe located in each of these walls and may be so adjusted as to permit a portion of the moisture-laden air to return to the heating chamber and draft inducing factor which it has just left. However, the larger amount of air and in many cases all of the air exhausted from each drying section will pass in an inclined direction through the exhaust passage 33 into the heating chamber 26 of the succeeding drying section where it again passes about a heating element 27 and through av draft inducing factor 28.

Fresh outer air is introduced to the dryer through openings 39 and 40 at the side of the last drying section, i. e. the section adjoining the exit end of the dryer. 'Ihe opening 39 is located adjoining the same casing while the opening 40 is located below the heating'coil 27 so that a portion of the fresh air is heated and a portion thereof is introduced directly to the draft inducing factor or blower without 'being heated. Thus as the air continues its movement in a direction which is approximately of spiral form and generally counter to the direction of article movement through the conveyor, it is rapidly heated as it takes upon additional moisture, the rise in temperature of `the drying medium obviously increasing its ability to take up moisture from the material to be dried.

The drying chamber adjoining the inlet end of the tunnel is provided with an exhaust passage 34 similar to that previously described which, however, sends the drying medium into the vertical passage 41, Fig. 2, whence it is directed by blower 43 into the elongate exhaust duct 44 which extends along the dryer in a direction substantially parallel to the path of article movement within the dryer. Adjoining theoutlet of'the dryer is a series of controllable dampers 47 which permit a portion of the air in exhaust duct 44 to be returned to the draft inducing factor 28 at the exit end of the tunnel. A suitable damper 49 is located between dampers 47 and the outlet of passage 44 so that additional means are provided for controlling the amount of air returnable to the last draft inducing factor from passage 4'4.

Fig. 4 shows a modified form of the invention in which a series of propellers 50 are used in place of the blowers 28 as draft inducing factors. In this form of the in vention, the rotor is not enclosed in a shroud or casmg.

It is evident that I have disclosed an improved drying apparatus and a method which permits the utilization of heated drying air in such-va manner as to attain the highest economy in operation and the most satisfactory of drying conditions, since the extent of air heating at various portions of the dryer may be regulated in accordance with the drying requirements at these particular regions. Thus, as the air gradually passes to the portion of the dryer where it .sweeps over articles having more moisture, the temperature of the air is raised by passing through successive heaters. However, a portion'of the air may be recirculated in the same heating section due to the arrangement of dampers 35, so that rate of air heating or of air movement through the dryer may be adjustably varied. The variable speed mechanism 20 permits variation of the'articles speed through the dryer in relation -to the amount of air supplied thereto, in order to permit the articles to occupy the necessary length of time for proper drying without remaining unnecessarily long within the dryer.

I claim:

l. Drying apparatus of the character described comprising an elongate drying chamber, conveyor means for carrying articles through the chamber, heating elements disposed along the chamber, and draft inducing factors arranged to circulate air over the heating elements and the articles upon the conveyor means, an exhaust duct for removing the moisture-laden air from the chamber, said duct extending along a considerableportion of the length of the dryer and means for permitting readmission of a art of the air in the exhaust duct to the dra t inducing factors. l

2. rying apparatus of the character described comprising an elongate drying chamber, conveyor means for carrying articles through the chamber, heatingelements disposed along the chamber, and .draft inducing factors arranged to circulate air over the heating elementsand the articles upon the conveyor means, an exhaust duct for removing the moisture-laden. air from the chamber, said duct extending along a considerable portion of the length of the dryer and means permitting readmission of a part of the air in the exhaust duct to the draft inducing factors, and means for admitting fresh air to the chamber.

3. Drying apparatus of the character described comprlsmg an elongate drying chamber, conveyor means for carrying articles through the chamber, a plurality of blowers disposed along the chamber, heating chambers adjoining each of said blowers, shrouds at the blower outlets directing air. transversely to the path of the articles being dried, inclined exhaust ducts below each of the heating chambers designed to exhaust the drying medium to an adjoining heating chamber, and an exhaust duct receiving air which has passed over the articles after leaving the last of said blowers, means permitting the return of a portion of the air from said duct to one of the blowers, and dampers controllable to permit the recirculll lation of a portion of the drying medium to the blower which it has just left.

4. Drying apparatus of the character described comprising an elongate drying chamber, conveyor means for carrying articles through the chamber, a plurality of blowers disposed along thechamber, heating chambers adjoining each of said blowers, shrouds at the blower outlets directing air transversely to the path of the articles being dried, inclined walls below each of the heating chambers, defined exhaust ducts opening 5 into adjoining heating chambers and designed to exhaust the drying medium into the same, and dampers in the inclined walls controllable to permit the return of a portion of the drying medium from the exhaust passage to the blower which it has just left.

Signed by me at North Adams, Massachusetts, this twenty-seventh day of July, 1927.

LUCIEN BUCK. 

